Specifications

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Cisco ONS 15454 Troubleshooting and Maintenance Guide
November 2001
Chapter 2 General Troubleshooting
Figure 2-8 Facility loopback on a destination DS-N card
Caution Performing a loopback on an in-service circuit is allowed but is service affecting.
Note Loopbacks operate only on in-service ports.
Step 1 Test the test set with a hard loop if you have not already done so.
To perform a hard loop on the test set, bridge the test set transmit (Tx) and receive (Rx) terminals with
an appropriate cable and send traffic across this loop to make sure the test set works properly.
Step 2 Use appropriate cabling to attach the electrical test set transmit (Tx) and receive (Rx) terminals to the
EIA connectors or DSx panel for the port you are testing. Both transmit (Tx) and receive (Rx) connect
to the same port. Set up your test set accordingly.
Step 3 In node view, double-click the card where you will perform the loopback.
Step 4 Click the Maintenance > Loopback tabs.
Note Loopbacks operate only on in-service ports.
Step 5 On the Loopback subtab, select Facility (Line) from the Loopback Type column for the port being
tested. If this is a multiport OC-N card, such as the OC3 IR 4 1310, make sure to select the row
appropriate for the desired port.
Step 6 Click Apply.
Step 7 On the confirmation dialog box, click Ye s.
Note It is normal for an alarm to appear during loopback. The alarm clears when you remove the
loopback.
Step 8 If the test set is not already sending traffic, send test set traffic on the loopback circuit.
Step 9 Examine the test traffic received by the test set. Look for errors or any other signal information that the
test set is capable of indicating.
Step 10 If the test set indicates a clean circuit:
a. Clear the facility loopback:
On the Loopback subtab, select None from the Loopback Type column.
DS-N OC-N
XC
ONS 15454
Source
OC-N DS-N
XC
ONS 15454
Destination
DS-N
DS-N
Facility loopback
Test Set A
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